1. Field of the Invention
The present invention relates to a method for positioning bioparticles, and more particularly to a method for controlling distribution and positions of the bioparticles with multi-phase electrical signals.
2. Description of the Related Art
In a vessel culture system, cells can obtain fresh nutrient supply from liquid medium; the way to make cells positioning and distribution uniformly becomes a major issue. Referring to FIG. 1, U.S. Pat. No. 6,653,124 discloses a vessel cell culture system. The vessel cell culture system has a plurality of individual arrayed cell culture rooms 1, and each cell culture room 1 has its own nutrient supply micro-channels 11. Although each cell culture room 1 disclosed in U.S. Pat. No. 6,653,124 can control nurturing environment individually, but it still has problems about dead places from sluggish floating medium, unbalanced nutrient supply, and cell deformation from extruding.
Referring to FIG. 2, a method for fixing cells 22 onto a biochip 20 with soft lithography is disclosed by Park T. H., and others, in Biotechnol. Prog. 2003, 19, 243-253. First, a stencil 21 with a micro-hole array structure is placed on the biochip 21. After the cell suspension is fastened in the openings formed of the micro-hole array structure of the stencil 21, the stencil 21 is removed to form a cell micro-array chip. Although the method can precisely position a group of cells in the openings, but can not control the uniformity of distribution of the cells.
U.S. Pat. No. 5,795,457 discloses a way to use dielectrophoresis (DEP) theorem to catch cells. Referring to FIG. 3, AC signals are applied unto adjacent castled electrodes 31, 32, and then under different AC frequencies, two different dielectric cells 35, 36 are caught and separated to different regions. The method disclosed in U.S. Pat. No. 5,795,457 uses non-mechanical and non-contact force to position cells, but it can not confirm uniformity of the cell distribution. Furthermore, a method for catching cells with DEP theorem is disclosed by Ozkan M. and others, in Langmuir 2003, 19, 1532-1538. The method adds AC signals to upper and lower electrodes to catch cells and position the cells on electrode array. But this method also can not confirm uniformity of the cell distribution.